The human brain contains an estimated 100 billion nerve cells (blue), as well as support cells known as glia (red and green). Neuroscientists are striving to understand how these cells are born, grow, connect and work together to give rise to our thoughts and actions. (Credit: NICHD/J. Cohen)

Neuroscience seeks to understand the most complex biological structure in the Universe, with an estimated 100 billion brain cells, or neurons, and trillions of connections between them. To make sense of the brain’s complexity, neuroscientists draw on expertise from numerous fields, including biology, physics and computer science, neurology, psychology and even philosophy. Some of the main questions they are trying to answer are: How does the brain, in which networks of cells course with electrical and chemical signals, give rise to the mind? How does the brain compute? How do we learn and remember (See "Memory")? What is the biological basis of language (See "Language")? And what causes psychiatric and neurological illnesses (See “Brain diseases & disorders”)?

Many neuroscientists feel the field is entering a new era, spurred by new technologies and techniques (See “Neurotechnology”) with which they can finally explore the working brain and begin to answer these questions. Hand in hand with this is a surge of interest in the field among graduate students, funding agencies as well as philanthropists and private enterprises. And, since 2013, a handful of big science project have launched to study the brain including the European Commission’s Human Brain Project to create a supercomputer simulation of the human brain and the U.S. Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative (See “BRAIN Initiative”) to develop new brain research tools, along with smaller efforts in Japan, Israel and China.

For the first time, scientists have watched sleep transform the brain. The research confirms a long-standing theory about the value of sleep—and helps explain why sleep deprivation messes with our ability to remember. Four neuroscientists—Chiara Cirelli, Graham Diering, Richard Huganir and Ken Paller—discuss two breakthrough sleep studies.

A group of scientists and funders—Walter Koroshetz (NIHO, James Olds (NSF), Christine Payne (Georgia Tech) and Terrence Sejnowski (Salk Institute)—reflect on what the BRAIN Initiative has already achieved and how it is evolving.

In a roundtable discussion, three leading scientists in the fields of neuroscience, brain imaging and cell biology weigh in on what it will take to find a cure for Alzheimer's and related neurodegenerative disorders.

In this live webcast, three of the scientists behind The Unified Microbiome Initiative proposal—Janet Jansson, Rob Knight and Jeff Miller—discuss how to unlock the power of the microbial communities that shape our world and influence our health.

A database of brain cells, and the new software platform that supports it, may finally reveal the cells’ identities—and supply scientists with a parts list for the brain. Christof Koch and Chinh Dang from the Allen Institute for Brain Science and Kenneth Harris from University College London explain.